This invention relates generally to a cannula or catheter that can be introduced to a small port and be inflated to accommodate a large flow of fluids, or can serve as a conduit or port to apply other medical therapy, such as surgical instruments, dilatation catheters, atherectomy devices, filters, aspirators, and pressure monitors.
Minimally invasive surgical procedures which use an endoscopic approach have been widely used in many surgical specialties, including cardiothoracic surgery. New surgical techniques and instruments have been developed especially to assist in minimally invasive coronary bypass grafting. This procedure is often performed using the port access approach where a minimal access incision is made in the intercostal space rather than the traditional midstemotomy approach, therefore minimizing trauma to the chest wall. After the incision is made, various instruments can be inserted through the incision and various tissue layers to reach the heart and great vessels. This peripherally-based system achieves aortic occlusion, cardioplegia delivery, and left ventricular decompression; thus, coronary revascularization and various cardiac procedures can be effectively performed.
Traditionally, flexible catheters or cannulas are fixed in their lumen and outside diameter size. In order to provide a large lumen for oxygenated blood flow during cardiopulmonary bypass (CPB), a traditional catheter or cannula is required to have a large diameter, therefore making insertion and tissue penetration difficult through a small port. A rigid trocar provides adequate luminal dimension; however, it is also limited in its ability to expand and provide easy access. Therefore, a need exists for a fluid or medical instrument delivery catheter or cannula having a flexible and expandable wall and a capability of achieving a minimal profile for entry through a small port, and having an ability to thereafter expand to accommodate a larger luminal diameter for delivery of fluid and instruments.
The present invention is particularly useful in minimally invasive coronary artery bypass grafting (CABG) since this procedure is generally performed through a small incision. In one embodiment, the invention provides a cannula comprising an elongate tubular member having a proximal end, a distal end, an expandable region, and a lumen. An elongated tubular or cylindrical balloon is disposed circumferentially about the expandable region of the tube. The cylindrical balloon has an inflation port and upon inflation itself expands and also causes the expandable region of the cannula to expand, thus enlarging the luminal diameter of the expandable region. The elongated cylindrical balloon is sealed at its ends to the outer wall of the cannula forming an inflatable space between the outer wall of the expandable region of the cannula and the inner wall of the cylindrical balloon.
In another embodiment, the invention provides an expandable lumen cannula comprising an elongate tubular member having an outer wall, a proximal end, a distal end, and a lumen therebetween. The elongate tubular member is expandable from a compressed condition to an expanded condition, and an elongate balloon having a proximal opening and a distal opening is circumferentially disposed about the elongate tubular member. A plurality of connections connect the outer wall of the elongate tubular member to the inner wall of the elongate balloon. Alternatively, the elongate balloon can be toroidal, forming a lumen from its proximal opening to its distal opening. In this embodiment, the outer wall of the elongate tubular member can be connected to the lumen of the elongate balloon through 1) a series of random connections, 2) a predetermined pattern of connections, or 3) in one continuous seal formed between the outer wall of the elongate tubular member and the lumen of the elongate balloon.
In another embodiment, a balloon occluder is mounted at the distal end of the cannula. Each of the balloon occluder and the cylindrical balloon has its own inflation port. In another embodiment, the cannula has an additional lumen extending distally from the proximal end to a port proximal to the balloon occluder for delivering cardioplegic solution. In other embodiments, the cannula will further include one or more helical threads disposed about the distal end of the tube proximal to the balloon occluder and distal to the cylindrical balloon.
In yet another embodiment, the present invention provides an expandable lumen cannula comprising a first elongate tubular member having a proximal end, a distal end, and a lumen therebetween, and a second elongate tubular member having an outer wall, a proximal end, a distal end, and a lumen therebetween. The second elongate tubular member is expandable and flexible. The proximal end of the second elongate tubular member is connected to the distal end of the first elongate tubular member, and their lumens are in fluid communication with each other. An elongate tubular or cylindrical balloon is disposed circumferentially about the second elongate tubular member, and a plurality of connections are formed between the outer wall of the second elongate tubular member and the elongate balloon.
The elongate balloon can be formed so that it has openings on its proximal and distal ends, which are sealed in a fluid-tight manner to the proximal and distal ends of the second elongate tubular member. A space can thus be formed between the outer wall of the second elongate tubular member and the inner wall of the elongate balloon. The connections can be between the outer wall of the second elongate tubular member and the inner wall of the elongate balloon. An inflation port in communication with the space formed between the second elongate tubular member and the elongate balloon can be used to inflate the elongate balloon with fluid. The fluid will be trapped in the space between the outer wall of the elongate tubular balloon and the inner wall of the elongate balloon and will cause an outward force, thus forcing the elongate balloon to expand and inflate. The inflation of the elongate balloon will in turn cause an outward force on the connections between the elongate balloon and the second elongate tubular member. This force will cause those connections to pull the wall of the second elongate tubular member radially outward, thus increasing the luminal diameter of the second elongate tubular member.
In an alternative embodiment, the elongate tubular or cylindrical balloon is toroidal in shape so that it forms a lumen from its proximal opening to its distal opening. The expandable lumen cannula is formed by inserting the second elongate tubular member through the lumen of the elongate balloon. In this embodiment, the connections previously described can be between the outer wall of the second elongate tubular member and the lumen of the elongate balloon. The outer wall of the elongate tubular member can also be sealed in a fluid-tight manner to the lumen of the elongate balloon, which can be one continuous seal along the entire length of the lumen of the elongate balloon. The elongate balloon can further comprise an inflation port for inflating the balloon.
The present invention provides an expandable lumen cannula which assists in minimally invasive aortic cannulation. The expandable lumen cannula is inserted through a port access, advancing the distal end into the ascending aorta. Fluid is introduced into the space formed between the inner wall of the cylindrical balloon and the outer wall of the flexible region of the cannula. The introduction of the fluid causes the cylindrical balloon and the flexible region of the cannula to expand, thereby causing the luminal diameter of the flexible region of the cannula to increase. Oxgenated blood then can be infused through the lumen of the cannula into the aorta. In alternative methods, the expanded lumen of the cannula can be used to insert medical devices for the performance of surgical procedures within the aorta, carotid arteries, or any other internal body structure accessible by cannulation.
In alternative methods, an expandable lumen cannula further comprises a balloon occluder at its distal end in fluid communication with an inflation lumen and an inflation port. The expandable lumen cannula is inserted through a port access, advancing the distal end into the ascending aorta. The balloon occluder is inflated to occlude the ascending aorta, followed by inflation of the cylindrical balloon, thereby increasing the diameter of the cannula lumen. Oxygenated blood then can be infused through the lumen of the cannula into the aorta distal to the balloon occluder. In alternative methods, the expanded lumen of the cannula can be used to insert medical devices for the performance of surgical procedures within the aorta, carotid arteries, or any other internal body structure accessible by cannulation.
It will be understood that there are many advantages to using an inflatable cannula as disclosed herein. For example, the inflatable cannula of the invention can be used (1) to provide easy introduction of the cannula through a small port, (2) to provide an expanding tube that serves to gently move nearby organs and tissues out of the path during surgery, (3) to provide a conduit or port to apply other medical therapies, e.g., surgical instruments, dilatation catheters, atherectomy devices, filters, aspirators, pressure monitors, etc., (4) to provide an inflatable lumen which can accommodate large flow of fluid, e.g., oxygenated blood, into the aorta or other internal body structure, (5) to provide better contact and therefore stabilization between the cannula and the arterial wall by having cannula threads at the point of contact with the vessel wall, (6) to provide interruption of arterial flow through inflating the balloon occluder, thus minimizing damage to the arterial wall and reducing the risk of emboli dislodgment as compared to traditional clamping.